A microfilm is used as one of means for conveniently storing records of many documents, prints, etc. This microfilm carries these records in a greatly reduced scale, so that the various picture image data recorded on the microfilm can be reenlarged to be projected on a screen or reenlarged to be copied by a copying apparatus when so required.
A conventional microfilm in the form of a silver-halide photosensitive member is defective in that, unlike a magnetic tape, once picture image data are recorded thereon, other required picture image data cannot be additionally recorded thereon or the picture image data already recorded thereon cannot be modified or corrected.
A microfilm in the form of an electrophotosensitive member permitting addition and modification or correction of recorded picture image data has been developed to obviate the defect of the conventional microfilm. This electrophotographic microfilm is formed by laminating a layer of a transparent conductive material and a layer of a transparent photoconductive insulating material on a base of a transparent insulating material. The electrophotographic microfilm has the feature of exhibiting photosensitivity when electrostatically charged. Another feature of the electrophotographic film is that it requires a short length of time and a narrow space for developing. Therefore, after recording a plurality of picture image data of different themes in spaced-apart relation on such an electrophotographic microfilm, relevant picture image data can be additionally recorded adjacent to the recorded picture image data as required.
Recording of picture image data on such an electrophotographic film requires electrophotographic processing means for performing the various steps of processing including electrostatic charging, exposure, developing and fixing of picture image data to be recorded on the electrophotographic microfilm. Also, reading of picture image data recorded on the electrophotographic film requires means for enlarging and projecting the picture image data recorded on the electrophotographic film. For this purpose, an electrophotographic camera processor-reader has been developed which is provided with both the electrophotographic processing means and the enlarging-projecting means above described.
FIG. 1 shows schematically the structure of one form of a prior art electrophotographic camera processor-reader. Referring to FIG. 1, an electrophotographic microfilm 101 in web or belt form is wound at both ends thereof around a pair of winding shafts 102 respectively, and these winding shafts 102 are supported so as to rotate in both the normal and reverse directions relative to a housing 103. An original-supporting glass plate 105, on which an original 104 is placed with its front side facing downward, is disposed on the upper part of the housing 103, and a light source or lamp 106 illuminating the original 104 is disposed beneath the original-supporting glass plate 105.
Along the electrophotographic microfilm 101 extending between the pair of winding shafts 102, a charger 107, a recording lens 108, a developer 109, and a fixing and projecting lamp 110 are disposed in the above order. The charger 107 acts to electrostatically charge the electrophotographic microfilm 101 to render the charged area photosensitive, and the recording lens 108 acts to focus picture image data carried by the original 104 onto the charged area of the electrophotographic microfilm 101. The developer 109 acts to toner-develop an electrostatic latent image of the picture image data formed on the electrophotographic microfilm 101, and the lamp 110 has the function of heat-fixing the toner image of the picture image data formed by the developer 109 on the electrophotographic microfilm 101 and functions also as an illumination light source for projection of an enlarged toner image with transmitted light. For this purpose, a heat shielding filter 111 is movably interposed between the electrophotographic microfilm 101 and the lamp 110 so that it can be brought to a non-heat-shielding position during the step of fixing and to a heat-shielding position during the step of projection. A projecting lens 112 is disposed opposite the illuminating lamp 110 on the other side of the electrophotographic microfilm 101, so that the toner image formed on the electrophotographic microfilm 101 can be projected through three reflecting mirrors 113 onto a translucent screen 114 as an enlarged image.
In such an electrophotographic camera processor-reader, replacement of the electrophotographic microfilm 101 requires the troublesome steps of unloading the electrophotographic microfilm 101 from the position wound around the winding shafts 102 and loading a new electrophotographic microfilm 101 to be wound around the winding shafts 102. In an effort to facilitate handling of an electrophotographic microfilm 101 in such an electrophotographic camera processor-reader, it has been proposed to accommodate the electrophotographic microfilm 101 in a cassette. In such a case too, it is also necessary that, for the purpose of reproduction or projection of picture image data recorded on the electrophotographic microfilm 101, light emitted from the projecting lamp 110 is transmitted through the electrophotographic microfilm 101. That is, the projecting lamp 110 and the projecting lens 112 must be disposed on both sides respectively of the electrophotographic microfilm 101 contained in the cassette. In order that the projecting lamp 110 and the condenser lens 112 can be inserted into the cassette, the cassette itself must be made bulky, resulting in the loss of one of the advantages of the microfilm according to which a quite narrow space is required. On the other hand, U.S. Pat. No. 4,324,484 discloses a cassette containing an electrophotographic microfilm therein. However, due to the fact that a processor assembly for making electrophotographic processing on the electrophotographic microfilm is incorporated in the cassette, the disclosed cassette is defective in that the size of the cassette becomes inevitably large, resulting in degraded portability and storability and also giving rise to an undesirable increase in the manufacturing cost.